<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            background-color: #000;
        }
        div {
            width: 200px;
            height: 200px;
            margin: 200px auto;
            box-shadow: 0 0 20px #237ad4 inset;
            background: linear-gradient(#1359df, #1359df) left top,
                linear-gradient(#1359df, #1359df) left top,
                linear-gradient(#1359df, #1359df) right top,
                linear-gradient(#1359df, #1359df) right top,
                linear-gradient(#1359df, #1359df) left bottom,
                linear-gradient(#1359df, #1359df) left bottom,
                linear-gradient(#1359df, #1359df) right bottom,
                linear-gradient(#1359df, #1359df) right bottom;
            background-repeat: no-repeat;
            background-size: 1px 10px, 10px 1px;
        }
    </style>
</head>

<body>
    <div>

    </div>
</body>

</html>